The process of this invention relates to forming an integral or one-piece tube having thickened end portions and an intermediate thin wall with one of the end portions of a greater O.D. diameter than the remainder of the tube so that the tube may function as a semi-float truck axle tube or a similar shaped device. The process is somewhat similar to, but an improvement relative to, the cold forming or extrusion process for forming tube enlargements disclosed in my prior U.S. Pat. No. 3,837,205 issued Sept. 24, 1974 and U.S. Pat. No. 3,886,649 issued June 3, 1975.
Tubes of the general shape contemplated herein, are commonly used for what are called semi-float truck axles. This is a long uniform O.D. tube of thin wall section having a thickened wall end section and a thickened wall, bell-shape expanded opposite end section which receives bearings, shaft inserts and the like. Such tubes have in the past been made of multiple sections which have been fastened together as by welding. These sections typically have been formed by forging processes or by machining processes or in separate sections by cold forming processes such as is described above in connection with my prior patents. However, in these types of tubes, it was necessary to form the cross-sectional wall thicknesses greater than required merely for strength purposes, because there have not been feasible ways of easily thinning out the tube areas where strength is not required. In addition, the expenses of making and assembling several sections have been considerable. Thus, the process herein contemplates producing a one-piece, generally thin wall elongated tube of uniform O.D. but with varying I.D.'s at one end and a flared or bell-formed opposite end. By this process, the tube is made in a simple, continuous and relatively inexpensive operation and is of lighter weight, as compared to tubes of prior processes.